The present disclosure relates to satellite communications in general, and in particular, to the positioning of satellite antennas.
As demand for satellite communications continues to grow, the use of spot beams in satellite systems has become increasingly popular. A spot beam is a modulated satellite beam focused on a limited geographic region of the Earth. By reducing the coverage area of the beam, a more directional antenna may be used by the satellite to transmit the beam to Earth. This higher gain associated with a spot beam may produce better signal-to-noise (SNR) ratio at a user terminal, which allows for higher rates of data transfer between the satellite and terminal. Also, the smaller size of spot beams allows for frequency reuse with limited inter-beam interference, thereby providing for even greater increases in data throughput at a satellite.
While spot beams can be very useful in areas of high demand, they may be susceptible to pointing errors. Satellite antenna movement within even a few thousandths of a degree may substantially change the coverage area of a spot beam on the earth. Moreover, it is often the case that multiple spot beams are transmitted in a predetermined pattern from the satellite to various intended coverage areas. Thus, an antenna pointing error at the satellite may detrimentally reduce the quality of communications over multiple spot beams simultaneously.